The boundaries of East Prussia, with the reservations made in Section IX (East Prussia) of Part III, will be determined as follows:
from a point on the coast of the Baltic Sea about 1½ kilometres north of Pröbbernau church in a direction of about 159° East from true North:
a line to be fixed on the ground for about 2 kilometres;
thence in a straight line to the light at the bend of the Elbing Channel in approximately latitude 54° 19½´ North, longitude 19° 26´ East of Greenwich;
thence to the easternmost mouth of the Nogat River at a bearing of approximately 209° East from true North;
thence up the course of the Nogat River to the point where the latter leaves the Vistula (Weichsel);
thence up the principal channel of navigation of the Vistula, then the southern boundary of the Kreis of Marienwerder, then that of the Kreis of Rosenberg eastwards to the point where it meets the old boundary of East Prussia.
thence the old boundary between East and West Prussia, then the boundary between the Kreise of Osterode and Neidenburg, then the course of the river Skottau downstream, then the course of the Neide upstream to a point situated about 5 kilometres west of Bialutten being the nearest point to the old frontier of Russia;
thence in an easterly direction to a point immediately south of the intersection of the road Neidenburg-Mlava with the old frontier of Russia:
a line to be fixed on the ground passing north of Bialutten;
thence the old frontier of Russia to a point east of Schmalleningken, then the principal channel of navigation of the Niemen (Memel) downstream, then the Skierwieth arm of the delta to the Kurisches Haff;
thence a straight line to the point where the eastern shore of the Kurische Nehrung meets the administrative boundary about 4 kilometres south-west of Nidden;
thence this administrative boundary to the western shore of the Kurische Nehrung.
The boundaries as described above are drawn in red on a one-in-a-million map which is annexed to the present Treaty (Map No 1.)
In the case of any discrepancies between the text of the Treaty and this map or any other map which may be annexed, the text will be final.
In the case of boundaries which are defined by a waterway, the terms „course“ and „channel“ used in the present Treaty signify: in the case of non-navigable rivers, the median line of the waterway or of its principal arm, and, in the case of navigable rivers, the median line of the principal channel of navigation. It will rest with the Boundary Commissions provided by the present Treaty to specify in each case whether the frontier line shall follow any changes of the course or channel which may take place or whether it shall be definitely fixed by the position of the course or channel at the time when the present Treaty comes into force.
Source: The Treaty of Peace with Germany, June 28, 1919, International Law Documents. Naval War College, Washington: Government Printing Office, 1920, pp. 18-21.